1. Field of the Invention
The present invention relates to the removal of offshore platforms and, more particularly, to the severing and removal of tubular pilings or pipe which support such platforms.
2. Description of the Prior Art
Offshore platforms which are used for the production of oil and gas from deposits below the ocean floor are commonly constructed by driving a section of tubular piling or pipe into the ocean bed a considerable distance followed by welding successive lengths of piling until the desired height is achieved, the piling serving as legs for the platform. Once the piling has been set, a framework is then attached to the legs and decking added to support the production equipment, housing facilities and the like. The offshore production platform is generally considered a permanent structure in the sense that it is erected at a single location and remains there as long as there is oil and/or gas production. However, once the oil and gas production plays out, the production platform must be removed since it may pose a hazard to shipping. Since many offshore oil and gas production areas are now reaching maturity, there are an increasing number of production platforms which must be removed.
The removal of an offshore platform presents several difficulties, not the least of which is the fact that the platform is erected in an environment which at times is harsh. Complicating the matter is the fact that it is generally required that the legs of the platform, i.e. the piling, be severed at a point far below, e.g. 15-20 feet, the ocean floor. One technique which has been used for severing the piling involves the use of explosives which are used to sever the piling at the desired point below the ocean floor. However, grave environmental damage can result from the use of this technique as it may result in the death of fish, sea turtles, porpoises, etc. Moreover, the use of subsea explosives in removing offshore piling can result in churning up mud, silt and sand from the ocean floor which can irrevocably damage sensitive coral reefs and the like. Lastly, the use of explosive techniques to remove the piling usually requires the use of deepsea divers with all the attendant hazards.